Small-Scale Thermal Treatment of Investigation-Derived Wastes (IDW) Containing Per- and Polyfluoroalkyl Substances (PFAS)
Paul Koster van Groos | Aptim
The primary objective of this project is to evaluate and demonstrate thermal treatment of investigation-derived wastes (IDW) containing per- and polyfluoroalkyl substances (PFAS). This demonstration proof of concept is the first step toward developing a small-scale and mobile thermal system capable of treating this IDW on-site. Small-scale thermal treatment directly addresses the Strategic Environmental Research and Development Program (SERDP) Statement of Need (SON) seeking innovative approaches for on-site and destructive treatment of IDW containing PFAS and other traditional Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) contaminants. Cost effective calcium hydroxide (i.e., slaked lime; Ca(OH)2) amendments will be utilized to lower thermal decomposition temperatures and reduce off-gases of potential concern. The research for this project includes Dr. Paul Koster van Groos (Lawrenceville, NJ) and Mr. Stuart Shealy, P.E. (Knoxville, TN) of APTIM Federal Services, LLC.
The technical approach for this project is focused on evaluating thermal decomposition of PFAS in IDW materials, and utilizing Ca(OH)2 amendments to lower energy use and reduce volatile organic fluorine (VOF) gases produced during such decomposition. The technical approach consists of the following specific technical tasks:
Task 1. Collect and characterize representative IDW materials
Task 2. Thermal decomposition studies of PFOA, PFOS, and Mixtures
Task 3. Thermal treatments of PFAS in representative IDW materials
Task 4. Reporting and project management
Tasks 2 and 3 contain the majority of the experimental effort. During Tasks 2 and 3, two furnaces will be placed in series, with aqueous solutions capable of trapping mineralized fluorine species (e.g., HF) located after each furnace. PFAS containing materials will be placed within the first furnace, where temperatures will be adjusted systematically to investigate thermal decomposition profiles. The second furnace in combination with trapping solutions will be utilized to examine the off-gas composition.
Thermal treatment systems are attractive for handling PFAS IDW because they can treat contaminant of concern (COC) mixtures with widely varying properties and operate at various scales, but drawbacks can include high energy usage and challenging air emissions. The primary benefits of this limited-scope project are: (1) to demonstrate complete thermal treatment of PFAS in IDW at conditions that are also amenable for other potential co-contaminants; and (2) to demonstrate that treatment temperatures and VOF off-gases can be reduced significantly with Ca(OH)2 treatment, which will reduce overall cost at scale and help to address air quality concerns associated with thermal treatment. The results of this limited scope study are expected to provide the data necessary to design a robust and mobile system for on-site treatment of IDW at Department of Defense facilities. (Anticipated Completion - December 2018)